This invention relates to a dialysis device and, more particularly, to an implantable subcutaneous device which is connected to an implanted peritoneal dialysis catheter and can be accessed percutaneously with a needle for performing fluid exchanges for peritoneal dialysis.
Presently, peritoneal dialysis is most commonly performed by using the Tenckhoff system that employs a dialysis catheter which has one end permanently implanted within the patient's peritoneal cavity. The other end of the catheter exits externally through the skin in the patient's abdomen, terminating in a section of tubing approximately 10 centimeters in length which is connected during dialysis to dialysate fluid. When the external portion of the catheter is not in use, it is curled on itself and taped to the skin.
There are numerous disadvantages to use of the Tenckhoff system which are primarily caused by having a portion of the catheter external to the patient's skin. First, the external portion of the catheter requires daily wound care at its exit site on the abdomen. Second, the presence of an external access device promotes infections both at the exit site and at the connector areas. Catheter exit site infections are directly caused by having the catheter exit through the skin, which area is chronically contaminated with bacteria. Episodes of peritonitis may also be caused due to break in the sterile technique at the catheter connector areas. Treatment of peritonitis necessitates an expensive drug regime to resolve the infection and, in extreme cases, may require removal of the catheter implant. Another problem with the use of an external catheter is that it causes a negative body image. Patients find them unsightly and embarrassing.
Foux U.S. Pat. No. 4,160,454 discloses an implantable catheter system which includes an elongate hollow casing 2 made of a material such as silastic rubber, that is implanted in the subcutaneous tissue of a patient. Extending generally at a right angle from one end of casing 2 is a tube 26, the interior of which communicates with the interior of casing 2 and is of sufficient length so that when casing 2 is implanted subcutaneously, tube 26 may extend into the peritoneal cavity of the patient. To provide rigidity, casing 2 is reinforced by a coil of wire 34 (shown by dotted line in FIG. 1) made of a material such as stainless steel.
There are numerous disadvantages, however, with the Foux device. First, because of the shape of Foux, only a small surface area of the device adjacent the patient's skin is presented for needle penetration. Because there is only a small skin area available for sticking, the area would not be allowed to heal before that area would need to be repunctured. Second, casing 2 appears to be cigar-shaped and substantially circular in cross section, such that correct placement of a needle into the interior of the device would be difficult because casing 2 would tend to rotate or move and would be difficult to pin down or stabilize just prior to needle penetration. With Foux, it would be difficult for the user to confirm whether the needle is in the proper position for fluid exchanges. Both because of the shape of the device and because it is reinforced only with a wire coil, it would be very easy for a needle to penetrate through the entire device and out the other side. Furthermore, Foux presents a unitary system which includes the subcutaneous access device as well as the peritoneal catheter and is not designed to be utilized with a previously implanted peritoneal dialysis catheter.
Accordingly, a general object of the present invention is to provide an access device that is located internally in the patient's subcutaneous tissue thereby eliminating the need for an external catheter and the problems associated therewith.
Another object is to provide a device with a large presentation area which can be easily accessed by the patient.
A further object is to provide an access device which is designed to facilitate correct needle placement and to give the patient prompt confirmation that the needle is correctly positioned.
Yet a further object of the present invention is to provide an access device which is suitable for repeated entries.
Yet another object is to provide a subcutaneous access device which can be retrofitted with a previously implanted peritoneal dialysis catheter.
In the present invention, there is provided a subcutaneous access device for connection to a peritoneal dialysis catheter which includes an elongate housing having a needle-impervious outer shell forming the sides and bottom of the housing. The housing further includes a top expanse connected at its periphery to the outer shell, which expanse is composed of a needle-permeable and self-sealing material and has extending substantially the length and breadth of said housing an expansive flat presentation region. A hollow central chamber, disposed intermediate the top expanse and the bottom of the shell, extends the length of the housing. The housing also includes a fitting which projects outwardly from the housing and is positioned to accommodate connection with an implanted peritoneal dialysis catheter.